It is often necessary to refurbish building exterior due to a variety of reasons, such as aging, cracking of the existing surface structure, updating of the building exterior to name only a few. Several approaches have been taken in providing a new exterior to an existing building, such as using prefab panels which are affixed to the building wall and other surfaces, or the application of a stucco finish to the building exterior.
Horbach, U.S. Pat. No. 3,389,518, discloses an approach which provides a continuous finish to the building exterior when completed. To the building exterior, a form of cellular insulation is applied by use of adhesives. A continuous layer of cementitious material is applied over the cellular insulation and reinforcement in the form of glass fibre fabric or reinforcing fibres is incorporated in the cementitious material. A finish coat of synthetic materials, such as propionic acid ester or other binder materials, is applied to the cementitious layer. The finish coat may include a mineral aggregate for decorative purposes. The purpose of this structure is to prevent crack propagation in the building wall being transmitted to the newly completed surface, thereby preventing crack formation in the new finish. Horbach refers to use of steel plates on the face of the insulation to protect the cellular insulation material. He does not recommend the use of such steel plates because of heat conductivity and that due to their exceptional weight, they have to be firmly secured to the building exterior and cannot compensate for temperature variations that can form cracks in the surface of finish material applied to the insulation.
Heck, U.S. Pat. No. 4,318,258, discloses improvements in the use of Styrofoam (trademark) panels which are affixed to building walls. The insulation panelling has a special grooving arrangement to compensate for expansion and contraction in the panels. A cement layer is applied over top of the foam layers. The plaster or mortar may contain synthetic resins, such as methyl cellulose and polyvinyl propionate. Other suitable plastic resins include homo- polymers, copolymers of acrylic acid and methacrylic acid, e.g. styrol acrylates and vinyl acetates. The foam slabs as grooved are glued to the building exterior in a manner similar to that discussed in Horbach, U.S. Pat. No. 3,389,518.
A comparable system involving the use of Styrofoam panels is disclosed in Canadian Pat. No. 1,148,324. The Styrofoam panels having grooves on the interior and the exterior are applied to a building wall using fasteners. The base coat of plaster or mortar is applied over the Styrofoam panels where the cementitious material is received in the outer grooves of the Styrofoam panels to ensure that the hardened base coat material is firmly affixed to the Styrofoam material. When the styrofoam material moves due to expansion and contraction caused by temperature extremes, cracking in the base coat occurs.
Burrows, U.S. Pat. No. 4,044,520, discloses a building panel system which is a modular unit glued to the building exterior. Each building panel as preformed consists of a foamed resin insulation layer over which a base coat and finish coat are applied. A polymer fortified concrete base coat may be used. Polymer fortification of the cement may be provided by an acrylic polymer together with a defoaming agent. The outer facing layer may be of a synthetic binder material, such as an acrylic polymer optionally used in combination with concrete. Aggregate may be added to the binder material to enhance the appearance of the building panels. These individual preformed panels have edge portions formed in a manner so that, when the panels are glued to the building exterior, the edges overlap in a mating manner to provide a modular type exterior finish for the building. The unfortunate problem with this system is that, if the building exterior is of uneven plane, then the panels as applied to the building exterior also take on the uneven plane of the building.
Another form of prefabricated building panel is disclosed in Australian Pat. No. 236,934. A prefabricated panel, according to this patent, consists of gluing together a mechanically resisting plate or slab and a heat and sound insulating layer. The building panel is impermeable to moisture, which can cause a problem when applied to building exteriors because moisture vapor should be allowed to freely diffuse into and out of the cladding applied to the building exterior.